The present invention relates to a damper which includes a movable sleeve rotatably received in a chamber and the speed of hydraulic oil in the chamber is different when opening and closing the pivotable object to which the damper is connected.
A conventional hinge has two plates which are respectively fixedly connected to a fixed object and a pivotable object so that the pivotable object is able to be pivoted about the hinge. However, during closing the pivotable object, the pivotable object could slam the fixed object because the user unintentionally releases the pivotable object at a speed. A huge noise is generated when the pivotable object is slammed and the pivotable object could be damaged if it is made of plastic material such as the toilet lid or the door of washing machines.
In accordance with one aspect of the present invention, there is provided a rotatable hydraulic damper which comprises a tubular fixed member in which a movable sleeve is movably received. A shaft has a passage defined longitudinally therethrough and includes a first section and a second section with a flange extending outward from the shaft and located between the first section and the second section. A plurality of radial holes are defined radially through the second section and communicate with the passage. A first seal bolt seals the passage at a distal end of the first section. A spring and a bead are received in the passage in the second section and the bead is urged by the spring and seals the passage at a distal end of the second section. The second section of the shaft is rotatably received in the fixed member via the open end of the fixed member and the open end of the fixed member contacts the flange.
A movable sleeve is movably mounted to the second section of the shaft and located between the inner periphery of the fixed member and the second section of the shaft. A plurality of longitudinal grooves are defined in an inside of the sleeve. A plurality of spiral teeth are defined in an outer periphery of the sleeve and engaged with the spiral grooves of the fixed member.
A cap has a hole and the first section extends through the hole in the cap and an inside of the cap contacts the flange. The cap is fixedly connected to the open end of the fixed member.
The primary object of the present invention is to provide a rotatable hydraulic damper which allows the pivotable object to be opened at a higher speed and a lower speed when is closed.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.